JP2002515527A - Polyol blends for producing open-celled rigid polyurethane foams - Google Patents

Abstract

(57) Abstract: (a) a polyol component having an average hydroxyl number of 150 to 850 mg KOH / g; and (b) comprising a polymer stably dispersed in a base polyol medium having an average primary hydroxyl content of less than 20%. A polyol blend. The polyol blend can be suitably used in a method for producing an open-celled rigid polyurethane foam, which is reacted with a polyisocyanate component in the presence of at least a catalyst, a cell stabilizer, and a blowing agent. The open-celled rigid polyurethane foam obtained in this way has a density of less than 50 kg / m ³ and a closed-cell content of less than 10% (preferably less than 5%) and can be suitably used as a thermal insulator.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a polyol blend for producing an open-celled rigid polyurethane foam, a method for producing an open-celled rigid polyurethane foam, a polyurethane foam obtained by the above-mentioned production method, and a molded article containing these polyurethane foams.

[0002] In general, rigid polyurethane foams are well known for having excellent heat insulating properties. In particular, closed cell polyurethane foams are widely used as insulation in, for example, piping, storage tanks, buildings, and refrigerators. Closed cell polyurethane foams are made using blowing agents based on chlorofluorocarbons (CFCs), often using R-11 (trichlorofluoromethane). The thermal insulation properties are largely determined by the thermal conductivity of the CFC gas filling the foam cells. However, as CFCs destroy the ozone layer, their use has become severely regulated from an environmental standpoint, and thus their use is now limited. Separately from this, the development of foaming agents is being promoted and actually being used.However, it is extremely difficult to develop a substitute having the same low thermal conductivity as CFC as a foaming agent. is there.

[0003] Although open-celled rigid polyurethane foams do not have as good thermal insulation properties as closed-celled rigid foams, their thermal conductivity is still sufficient for use as a thermal insulator. Furthermore, the dimensional stability at low foam densities of the open-cell foam is better than that of the closed-cell foam. Therefore, open-celled rigid polyurethane foams are very suitable for application as core material in vacuum insulation panels. Such panels typically include a core material encapsulated in a vacuum container of metal film and / or plastic film. Open-celled rigid polyurethane foams can also be used in rigid foam applications (eg, headliners or packages for automobiles) where less thermal insulation properties are required but some degree of structural support is required.

[0004] Several methods have been proposed for producing open cell rigid polyurethane foams. For example, EP-A-0,547,515 discloses a method for producing an open-celled rigid polyurethane foam, and according to the patent document, a polymethylene polyphenylisocyanate prepolymer and a polyol are used as a catalyst, a cell stabilizer, and a cell-communicating agent. Agent (cel
l The reaction is carried out using water as the sole blowing agent in the presence of an opening agent. Suitable cell communicating agents are divalent metal salts of fatty acids (eg, calcium stearate, magnesium stearate, strontium stearate, or calcium myristate).

[0005] According to EP-A-0,567,027, open-celled rigid polyurethane foams have a specific polyol mixture (having a hydroxyl number of from 160 to 360 mg KOH / g) comprising two or three polyols having different hydroxyl numbers. ) And by using water as a blowing agent.

[0006] Another method is described in EP-A-0,581,191, according to which a prepolymer and a polyol obtained by reacting polymethylene polyphenyl polyisocyanate with a monohydric alcohol are reacted with a polyol. An open-celled rigid polyurethane foam is produced by reacting using a CFC-substitute as a blowing agent in the presence of a catalyst, a cell stabilizer, and a cell opener. Suitably, the cell communication agent is a divalent metal salt of a fatty acid (eg, calcium stearate).

[0007] G. Burkhart and H. Schator, "35th Annual Polyurethane Technology / Marketing Conference Annual Report, September 12, 1994, pp. 311-315" describe a method for producing open-celled rigid polyurethane foams. According to the manufacturing method, an open cell structure is achieved by using a specific antifoaming agent (ie, Tegostab 8919; Tegostab is a trademark) in combination with a suitable silicone surfactant.

[0008] Although these methods are effective in producing open-celled rigid polyurethane foams, there is still room for improvement. It would be beneficial to have an open-celled rigid polyurethane foam that combines very low density with excellent mechanical or structural stability. This is because such low-density foams are attractive for use in a variety of applications, including as insulation. Low density is particularly desirable because the low weight of the foam facilitates, for example, transport and handling of the insulation panel. Low density also means that less starting material is required to produce the same volume of foam as compared to attempting to produce a higher density foam. This is clearly advantageous from an economic point of view. Furthermore, if low-density open-celled rigid foams are obtained without the need for any cell openers or defoamers, and therefore superior foams and easier production, these points are attractive. Will be.

Accordingly, the present invention relates to a polymer component comprising: (a) a polyol component having an average hydroxyl number of 150 to 850 mg KOH / g; and (b) a polymer stably dispersed in a base polyol medium having an average primary hydroxyl content of less than 20%. And a polyol blend comprising:

[0010] The invention is essentially directed to a rigid polyol component (component (a))
And a specific polymer polyol (component (b)) (usually used in the production of flexible polyurethane foam). This particular combination of polyols has been found to provide an open cell rigid foam with excellent properties without the use of cell openers or defoamers.

Although the amounts of polyol and polymer polyol used can vary over a wide range, the polyol blends according to the invention are preferably prepared per 100 parts by weight of polyol component (a).
It comprises 2 to 25 parts by weight, more preferably 2 to 10 parts by weight of polymer polyol (b). The polyol component (a) can be any rigid polyol having an average hydroxyl number of 150 to 850 mg KOH / g, or a combination of rigid polyols. Such hard polyols are known in the art. Typical rigid polyols that can be suitably used in the polyol blends of the present invention are polyoxyalkylenes having a nominal molecular weight of 300-1500 (preferably 500-1000) and a nominal average functionality of 2.0 or more (preferably 2.5-6). It is a polyol. For the purposes of the present invention, the average hydroxyl number preferably has a value in the range from 150 to 650 mg KOH / g. The polyol component (a) may include a single hard polyol, or may include two or more hard polyols. In a preferred embodiment, the polyol component (a)
Comprises a polyol having a hydroxyl number of 150-400 mg KOH / g and a polyol having a hydroxyl number of 400-650 mg KOH / g. An example of a rigid polyol having a lower hydroxyl value is CARADOL GB250-01, and examples of a rigid polyol having a higher hydroxyl value are Carador LP530-03 and Carador LP585-01 (Caradol is a trademark. ).

The polymer polyol used as component (b) may generally be any polymer polyol containing a polymer stably dispersed in a base polyol medium, provided that the base polyol medium is Based on the total amount of hydroxyl groups present on the polyol forming the base polyol medium
The condition that it has an average primary hydroxyl content of less than 20% must be met. Therefore, the average primary hydroxyl content of one or more polyols is 20%
If less (preferably less than 10%, most preferably less than 5%), the base polyol medium may consist of one or more polyols. Polymer polyol component (b)
Suitably comprises a base polyol medium and a polymer stably dispersed in said base polyol medium in an amount of 5 to 40% by weight, based on the total weight of the polymer polyol. In another preferred embodiment, the base polyol medium is 250-12,000 (preferably 500-6,500, more preferably 2,500-6,000).
Molecular weight in the range of 2.0 or more (more preferably 2.5 to 6.0, most preferably 2.5 to 3.5
)) And a primary hydroxyl content of 10% or less (more preferably 5% or less). Very good base polyols are those with a very low ethylene oxide (EO) content obtained by EO chipping, since the base polyol medium most preferably has a very low average primary hydroxyl content. Suitably the ethylene oxide content obtained by ethylene oxide chipping is less than 1% by weight, and most preferably the polyols are not all tipped with EO.

[0013] The polymer stably dispersed in the base polymer medium may generally be any polymer known to be applicable for this purpose. Accordingly, suitable polymers include those based on ethylenically unsaturated monomers, especially vinyl aromatic hydrocarbons (e.g., styrene, α-methylstyrene,
Methyl styrene, and various other alkyl-substituted styrenes). Of these, styrene is preferably used. Vinyl aromatic monomers can be used alone or with other ethylenically unsaturated monomers such as acrylonitrile, methacrylonitrile, vinylidene chloride, various acrylates, and 1,3-
And conjugated dienes such as butadiene and isoprene. However, preferred polymers are polystyrene and styrene-acrylonitrile (SAN) copolymer. Other suitable types of polymers are polyurea polymers and polyurethane polymers. In particular, condensation products of polyhydric alcohol amines and aromatic diisocyanates are very useful in this regard. A highly preferred polymer is the condensation product of triethanolamine and toluene diisoyanate (TDI). For the purposes of the present invention, the polymer dispersed is preferably a polystyrene, a SAN copolymer, a polyurea or a polyurethane polymer obtained as a condensation product of triethanolamine and toluene diisocyanate.

The polymer to be dispersed is 5 to 40% by weight based on the total weight of the polymer polyol
Suitably it is present in an amount of When the polymer is a polyethylene or SAN polymer, the preferred amount of the polymer is 5 to 35% by weight, and when the polymer is a polyurea polymer or a polyurethane polymer, the preferred amount of the polymer is 5 to 20% by weight.

[0015] The polyol blends according to the invention are very suitable for producing open-celled rigid polyurethane foams. Accordingly, the present invention further provides at least a catalyst,
The present invention relates to a method for producing an open-celled rigid polyurethane foam, comprising reacting the polyol blend with a polyisocyanate component in the presence of a cell stabilizer and a foaming agent.

The polyisocyanates that can be used are those conventionally used in the production of rigid polyurethane foams. Useful polyisocyanates must have at least two isocyanate groups and are known in the art to be suitably applicable to the production of rigid polyurethane foams. -, Tri-, tetra-, and higher isocyanates. Mixtures of two or more of such aliphatic and / or aromatic polyisocyanates can also be used. Examples of suitable polyisocyanates include 2,4-toluene diisocyanate (2,4-TDI), 2,6-TDI, 2,4-TDI and 2
, 6-TDI, 1,5-naphthalenediisocyanate, 2,4-methoxyphenyl diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), 4,4′-biphenylenediisocyanate, 3,3′-dimethoxy- 4,4'-biphenylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4 ', 4 "-triphenylmethane triisocyanate Isocyanate, 2,4,6-toluene isocyanate, 4,4'-dimethyl-2,2 ', 5,5'-diphenylmethane tetraisocyanate, polymethylene-polyphenylene polyisocyanate, and mixtures of two or more of these High molecular weight MDI (mixture of polyisocyanate and MDI as the main component) can also be used, it has been found to be particularly advantageous to use high molecular weight MDI for the purposes of the present invention. There.

The amount of the polyisocyanate component used is such that the isocyanate index is 50 to 150.
Is appropriate and an amount such as 80-130 is most appropriate. However, isocyanate indexes beyond these ranges can be used.

[0018] Catalysts for making rigid polyurethane foams are known in the art and include many different compounds. Suitable catalysts for achieving the objects of the present invention include tertiary amines such as bis (2,2'-dimethylamino) ethyl ether, trimethylamine, triethylamine, triethylenediamine, and dimethylethanolamine (DMEA). Tin-based catalysts can also be used, such as tin salts of carboxylic acids and dialkyltin salts. Specific examples include dibutyltin dilaurate, stannous octoate, stannous oleate, dibutyltin acetate, and dibutyltin diacetate. In addition, trimerization catalysts such as potassium acetate can be used. The catalyst is usually used in an amount of 0.01 to 7 php (parts by weight per 100 parts of polyol).

The cell stabilizer (ie, surfactant) used in the process of the present invention can be any polyurethane foam stabilizer useful in making rigid polyurethane foam. Organosilicone or organopolysiloxane surfactants are most widely used as foam stabilizers in polyurethane production. Many types of such surfactants are commercially available. Usually such foam stabilizers are used in amounts up to 3 php.

In the production method of the present invention, a blowing agent is also used. Suitable blowing agents include water,
Acetone, (liquid) carbon dioxide, halogenated hydrocarbons, aliphatic alkanes (e.g., n
-Pentane and isopentane), and alicyclic alkanes (eg, cyclopentane and cyclohexane). It goes without saying that these foaming agents can be used alone or as a mixture of two or more. The use of water as the sole blowing agent has proven to be particularly advantageous in achieving the objects of the present invention. Although the amount of water used can be varied over a wide range, very good results have been obtained when using water in amounts of 2 to 12 php.

In addition, other well-known auxiliaries (eg flame retardants, antioxidants, colorants,
And fillers) can also be used. In a further aspect, the present invention relates to an open-celled rigid polyurethane foam obtained by the above process, having a density of less than 50 kg / m ³ and a closed-cell content of less than 10% (preferably less than 5%). Foam obtained by the production method of the present invention,
Preferably has a density of 10 to 30 kg / m ^3, more preferably have a density of 10~25kg / m ^3.

The invention further relates to a shaped article comprising the open-celled rigid polyurethane foam specified in the above paragraph, and to a thermal insulation comprising the thin open-celled rigid polyurethane foam in a laminated structure.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these specific embodiments. The components used in the examples are as follows.

Polyol Component Polyol A: A propylene oxide (PO) based rigid polyether polyol containing aromatic amine groups. It has a hydroxyl number of 530 mg KOH / g.

Polyol B: Rigid polyether polyol starting from glycerol. Has a hydroxyl number of 250 mg KOH / g. PP-A: (i) essentially 0% primary hydroxyl content, molecular weight of 3500, and 37 mg KO
Having a hydroxyl number of H / g, a base polyol which is an EO / PO-based polyether polyol starting from glycerol; and (ii) 20% by weight of polystyrene stably dispersed in the base polyol. Poly polyol.

PP-B: a polymer polyol containing (i) the same base polyol as in PP-A; and (ii) 40% by weight of a styrene-acrylonitrile copolymer stably dispersed in said base polyol.

PP-C: (i) EO starting from glycerol having a primary hydroxyl content of 80%, a molecular weight of 4700 and a hydroxyl number of 25 mg KOH / g and containing 14% by weight of EO chips A base polyol that is a / PO-based polyether polyol;
And (ii) 28% by weight of polystyrene stably dispersed in the base polyol;
A polyopolyol.

PP-D: (i) the same base polyol as in PP-C; and (ii) 15% by weight of a styrene-acrylonitrile copolymer stably dispersed in said base polyol;
A polyopolyol.

Auxiliary chemicals DMEA: dimethylethanolamine AM58: trimerization catalyst (commercially available from Resina Chemie) TCPP: tris (chloropropyl) phosphate (flame retardant) B8404: Tegostab B8404 (silicone interface) Activator). Commercially available from Goldschmidt.

Isocyanate MDI: High Molecular Weight Diphenylmethane Diisocyanate Example 1 A polyol formulation was prepared consisting of 30 parts by weight (pbw) of polyol A, 70 pbw of polyol B, and 10 pbw of PP-A. Next, a foaming compound (EX-1) having the composition shown in Table I was prepared.

The foaming formulation was foamed in a bag. After foaming, take a foam sample,
The density and closed cell content were measured. Example 2 The procedure described in Example 1 was repeated, except that 10 pbw of PP-B was added instead of PP-A (EX-2).

The composition of the foaming formulation and the properties of the resulting foam are shown in Table I. Comparative Examples 1 and 2 The procedure described in Example 1 was repeated except that 10 pbw PP-C (CEx-1) or 10 pbw PP-D (CEx-2) was used instead of 10 pbw PP-A. Was.

The composition of the foaming formulation and the properties of the resulting foam are shown in Table I.

[0034]

[Table 1]

From Table I it can be seen that the use of the polyol formulation according to the invention results in a foam having a slightly lower density and a much lower closed cell content. Example 3 A laminate comprising an open-cell polyurethane foam produced using the polyol blend of the present invention was produced using a continuous laminating machine.

The laminating machine is a high-pressure multi-component unit, manufactured by Cannon / Viking UK. The urethane system is a blend of four different streams, dispensed on bottom facing via perforated tubes (connected to a traversing mixing head). Kraft paper coated with polyethylene was used as facing. At a target density of 22 kg / m ³ and a belt speed of 2.9 m / min, the discharge rate of the machine was adjusted so as to obtain a laminate having a thickness of 60 mm and a width of 600 mm. The 6 meter conveyor section was operated in free rise mode.

As described above, the four streams (“polyol blend”, “cat 1 blend”, “
cat 2 blend, and "MDI") were pumped into the mixing head where they were thoroughly mixed and distributed over the facing.
And The composition of the other three streams is shown in Table II. The amounts are given in parts by weight (pbw).

[0038]

[Table 2]

The discharge amount of the flow was as follows. Discharge rate of polyol blend: 0.84 l / min MDI discharge rate: 1.08 l / min cat 1 blend discharge rate: 0.136 l / min cat 2 blend discharge rate: 0.033 l / min The temperature of the polyol blend stream and MDI stream is 19 ° C and belt temperature 35
C. was maintained.

The properties of the laminate based on open-celled rigid foam were as follows: Density: 22 kg / m ³ closed cell content: 2% compressive strength rise direction (rise direction): 80kPa direction of production (production direction): 55kPa side direction (side direction): 24 at 55 kPa Temperature 70 ° C. and 95% relative humidity Dimensional stability after time Rise direction: 3.5% Production direction: -0.5% Side direction: -0.7% Thermal conductivity at 10 ° C: 35mW / (mK) (One has a temperature of 0 ° C. and the other has a temperature of 20 ° C.), per second, per meter of laminate, 1K
Was determined by measuring the amount of heat transferred from the hot plate to the cold plate through the laminate per Kelvin temperature difference.

From these data, it can be seen that this laminate not only has a relatively low density and low closed cell content, but also exhibits excellent mechanical stability and low thermal conductivity, and is therefore extremely useful as a thermal insulator. Become.

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR , BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS , JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZA, ZWF term (reference) 4J002 AA003 BC033 BC06Y CH02W CH02X ER006 4J034 BA07 DC50 DG02 DG03 DG04 DG08 DG09 HA01 HA07 HA08 HA09 HC12 HC13 HC64 HC67 HC71 KB02 KC17 KD02 KD12 MA22 MA24 NA03 NA05 QA02 QA05 QB16 QC01 RA10 RA15

Claims (17)

[Claims] 1. A polymer comprising: (a) a polyol component having an average hydroxyl number of 150 to 850 mg KOH / g; and (b) a polymer stably dispersed in a base polyol medium having an average primary hydroxyl content of less than 20%. A polyol blend. 2. The polyol blend according to claim 1, comprising 2 to 25 parts by weight of the polymer polyol (b) per 100 parts by weight of the polyol component (a). 3. The polyol according to claim 1, wherein the polyol component (a) comprises a polyol having a hydroxyl number of 150 to 400 mg KOH / g and a polyol having a hydroxyl number of 400 to 650 mg KOH / g. blend. 4. A method according to claim 1, wherein the polymer polyol (b) has an average primary hydroxyl content of 10% or less, and the base polyol medium has an amount of 5 to 40% by weight based on the total weight of the polymer polyol. And a polymer stably dispersed in the polyol blend. 5. The polyol blend according to claim 4, wherein said base polyol medium has an average primary hydroxyl content of 5% or less. 6. A base polyol wherein the polymer polyol (b) comprises a polyoxyalkylene polyol having a molecular weight in the range of 250 to 12,000, an average nominal functionality (Fn) of 2.0 or more, and a primary hydroxyl content of 10% or less. The polyol according to any one of claims 1 to 5, comprising a medium and a polymer stably dispersed in the base polyol medium in an amount of 5 to 40% by weight based on the total weight of the polymer polyol. blend. 7. The polyol blend of claim 6, wherein said polyoxyalkylene polyol has a molecular weight in the range of 2,500 to 6,000, an Fn in the range of 2.5 to 3.5, and a primary hydroxyl content of 5% or less. 8. The polyol blend according to claim 6, wherein the polyoxyalkylene polyol has an ethylene oxide content from ethylene oxide chips of less than 1% by weight. 9. The polymer of claim 4, wherein the stably dispersed polymer is a polystyrene, a SAN copolymer, a polyurea, or a polyurethane polymer obtained as a condensation product of triethanolamine and toluene diisoyanate. The polyol component according to any one of the above. 10. An open-cell hard comprising reacting the polyol blend according to any one of claims 1 to 9 with a polyisocyanate component in the presence of at least a catalyst, a foam stabilizer, and a foaming agent. Manufacturing method of polyurethane foam. 11. The method according to claim 10, wherein said polyisocyanate component comprises high molecular weight MDI. 12. The method according to claim 10, wherein the blowing agent is water. 13. The process according to claim 12, wherein the water is present in an amount of 5 to 12 parts by weight per 100 parts by weight of the polyol component (a). 14. The polyurethane foam according to claim 1, having a density of less than 50 kg / m ³ ,
An open-celled rigid polyurethane foam obtained by the process according to any one of claims 10 to 13, having a closed cell content of less than 5%, preferably less than 5%. 15. The open-celled rigid polyurethane foam according to claim 14, having a density of 10 to ³⁰ kg / m ³ . 16. A shaped article comprising the open-celled rigid polyurethane foam according to claim 14. 17. A heat insulating material in a laminated structure, comprising the open-celled rigid polyurethane foam according to claim 14.